1. Field of the Invention
The present invention relates to a highly sensitive fluorescent label having a structure in which numerous phosphors are bound to a hydrophilic polymer via a polyether derivative, and also relates to a fluorescently labeled recognition substance labeled with the fluorescent label.
The present invention claims priority on Japanese Patent Application No. 2005-126247, filed on Apr. 25, 2005, the content of which is incorporated herein by reference.
2. Description of the Related Art
In the prior art, a method in which antigens or antibodies are labeled with radioisotopes, enzymes, phosphors, or the like and the intensity of signals emitted from these labels is measured is used so as to measure the concentration of the antigens or antibodies. However, the method using radioisotopes requires specific equipment and devices, and so has been scarcely used in recent years. Although a method exhibiting high sensitivity using luminous substrates has been widely used as the method using enzymes for labeling, the method requires expensive substrates and a relatively long time period for reacting the enzymes with the substrates, and so measurement cannot be performed over a short time.
In contrast, although the method using phosphors for labeling does not require specific equipment or devices or expensive substrates, it exhibits low sensitivity. In order to increase the sensitivity, it is required to introduce numerous phosphors into antibodies or the like. However, when numerous phosphors are directly bound to antibodies or the like, a quenching phenomenon occurs decreasing the fluorescence intensity, and the antibodies into which the phosphors are introduced gain increased hydrophobicity and are denatured. In order to solve this problem, a method in which a linker of a hydrophilic polymer is introduced into an antibody or the like and numerous phosphors are introduced into this linker has been proposed (see, for example, Japanese Unexamined Patent Application, First Publication No. S58-79162).
Although the above-mentioned method can prevent denaturation of the antibody or the like and decrease of the fluorescence intensity, a fluorescent label which can exhibit a higher fluorescence intensity is desired so as to improve the utility thereof.